Gujarat Earthquake 2001, India
Date: 26 January 2001
Epicentre: SSW of Chobari, Gujarat
Time: 03:16:40 UTC (08:46:40 IST)
Latitude: 23.442 (ISC)
Longitude: 70.310 E (ISC)
Depth: 16 kms (ISC)
Magnitude: Mw 7.7 (HRV), 7.6 (NEIC)
As Indians were celebrating their 51st republic day, a major earthquake turned all their happiness to unforgettable sorrow. A major earthquake struck Gujarat on 26th Jan 2001 at 8:46AM resulting in close to 13,820 deaths and extensive damage to property in Gujarat. Damage to a lesser extent also occurred in adjoining states of Madhyapradesh, Maharashtra and Rajasthan in India. This effect was also seen in Sindh province and Pakisthan. The earthquake had a magnitude of Mw= 7.7 and was felt for many minutes in many parts of South Asia. This is one of the largest instrumented earthquakes in Peninsula India.
The earthquake was centred 9.2 kilometres SSW of Chobari, Gujarat, India. It also centred in many other locations like, Bhachau, Gandhidham, Anjar, Bhuj, Morbi, Jamnagar, Ahmedabad, Hyderabad, Karachi, Delhi. This also affected Santa Cruz airport of Mumbai, India.
Seismological Aspects: (Causative fault, blind thrust event, ground motions)
is believed to have occurred on the south dipping North Wagad reverse fault in the Kutch aulocogen or failed rift. This has been further confirmed by after shock studies following the earthquake. Intial speculation held the Kutchh Mainland fault (KMF) responsible, further studies and field observations show that it might have been caused on the previously unknown NWF lying on the vicinity of the KMF. Slis is belived to have totalled between 1 metre to 4 metres. The rupture is also belived to have approached within 9 to 15 kilometres of the ground surface. Earthquakes on unknown faults are not uncommon and have occurred in the best studied places, such as the 1994 Northridge earthquake in the heavily instrumented Los Angeles area. The earthquake is an inraplate event, as it occurred within the Indian plate, away from its edges. Other studies are also of the opinion that the earthquake occurred in the diffused western boundary of the Indian plate.
Shaking effect: (Within Gujarat)
The worst damage was caused in eastern Kachchh, in the vicinity of the town of Bhachau which was almost completely destroyed. Kachchh was cut off from the rest of the country for more than 24 hours. At Anjar, much of the old section of the town was destroyed. At least 143 students and teachers, who were participating in a Republic day parade were killed at Khatri Chowk in Anjar, when buildings on both sides on the narrow lane they were in collapsed. The larger towns of Gandhidham and Bhuj were also badly affected. Many multi-storied buildings collapsed, including the housing quarters at the Indian Air Force base and the 8-storey Sahajanand colmplex in Bhuj. The worst damage was concentrated in the old city of Bhuj. Jubilee hospital, the main hospital in the city was levelled and so were many other medical facilities across Kachchh. Many of the injured were flown to Mumbai and Pune for medical treatment. Relief was flown in the Indian Air Force, from its bases in Amritsar, Bhatinda, Chandigarh and Pune. Structures of Historical impportance such as the famous Aina mahal and the Kachchh museum were heavily damaged and partially collapsed. the Chhatris at the Bhuj Fort were also either completely destroyed or very badly damaged. The port of Kandla was closed following the earthquake. About 2 thousand metric tonnes of Acrylonitrate (ACN), a highly toxic and flammable chemical leaked at the J.R Enterprises Tank farm, Knadla. Another tank, containing HEP (Paraffin) in the same tank farm also leaked. No fires were reported from industrial facilities. Sporadic damage occurred all across Gujarat. At Morvi, many historic buildings collapsed and heavy damage occurred at the famous Green Chowk market. The most significant damage however, occurred in the two large cities of Ahmedabad and Surat.
Shaking effect: (Outside Gujarat)
Outside Gujarat, to the west, strong shaking was experienced in the Indus delta and the large cities of Karachi and Hyderabad. 18 people were killed in the sindh. A 7-storey building, Ghousia Apartments collapsed in the city of Hyderabad. Liquefaction, earthquake fountains and sandblows were also reported from here. In Rajasthan, many buildings were badly damaged, mainly at Bakhasar and Jodhpur. Many structures of historical importance, like the Jaiselmer Fort, were damaged in Rajasthan. Damage was also reported from Mt. Abu, Pokhran, Jodhpur, Jaipur and Udaypur. In Madhyapradesh tremors were felt prominently in the Narmada Valley, as far as Jabalpur. In Maharashtra, buildings developed cracks at many places in Mumbai and Vashi. A fire bregade station suffered slight structural damage at Wadala, Mumbai. Tremors were felt strongly in Mumbai, Pune and as far as Kolhapur. Beyond these areas, the shock was felt to limited extent in Hyderabad (A.P) and Bengalooru, and in high-rise buildings as far as Kolkata and New Delhi. Long period effects such as a sensation of nausea / giddiness among people and oscillating hanging objects were reported from many parts of India, Pakistan, Bangladesh and Nepal. Press reports from Bangladesh, reported unusual drifts in rivers in the Sunderbans following the earthquake. Even at locations over 1,000 kilometres from the epicentre, ground shaking was amplified in recent sediments resulting in locally moderate shaking. Such effects were experienced in the Kaveri delta of Tamil Nadu, in the Bengal basin and in the Kathmandu Valley in Nepal.
Effect on public infrastructure:
The Atomic Energy Regulatory Board (A.E.R.C) reported no damage from the nuclear power stations at Kakrapara (Gujarat), Rawatbhata (Rajasthan), Tarapur (Maharasthra), Narora (Uttar Pradesh), Kalpakkam (Tamil Nadu) and Kaiga (Karnataka). The department of Atomic Energy (D.A.E) said that the Kakrapara nuclear reactor, at Anumala near Surat withstood the earthquake and was functional after the earthquake. The level of shaking is reported to have reached 51.2 Hz, very close to the tripping level. Several dams, such as Suvi and Tappar dams, were damaged in the epicetral area. Nearly 200 dams were damaged and required to either be repaired or strengthened. The intake tower of the Tappar dam near Gandhidham was heavily damaged. Water supply was disrupted in Kutchh due to damage caused to the water pumping and pipe transmission system. The elevated water tanks collapsed in the epicentral area, though 100 others survived without any major damage. 5 tanks also collapsed in the epicetral area. Such a structure was seen swaying during the mainshock at Radhapur. 16 out of 300 well inspected following the earthquake had sulphur problems. Highways were still functional. The Surajbari Bridge on National Highway 8A, suffered serious structural damage and traffic movement was restricted on it. A major power failure was experienced all over Gujarat immediately following the earthquake. Tele communication networks were temporarily distrupted and the fibre optic lines served. However, services were restored by within a week as was a cellular phone service.
The strongest aftershock occurred on January 28, 2001 and was centred near Bhachau. It had a magnitude of Mw-5.8 and caused widespread panic in Gujarat. People rushed out into the open in Ahmedabad where the aftereshock was felt for 30 seconds. It was also felt at Jaisalmer in Rajasthan and as far away as Mumbai. Many people were injured at Ahmedabad, in an M5.3 aftershock on February 8, 2001, as they jumped from buildings in panic. An aftershock on February 24, injured several people in Sindh, Pakisthan and caused some damage to buldings in the area.